# Rémi Flamary

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### Submited and preprint

R. B. Metcalf, M. Meneghetti, C. Avestruz, F. Bellagamba, C. R. Bom, E. Bertin, R. Cabanac, E. Decencière, R. Flamary, R. Gavazzi, others, The Strong Gravitational Lens Finding Challenge, arXiv preprint arXiv:1802.03609, 2018.
Abstract: Large scale imaging surveys will increase the number of galaxy-scale strong lensing candidates by maybe three orders of magnitudes beyond the number known today. Finding these rare objects will require picking them out of at least tens of millions of images and deriving scientific results from them will require quantifying the efficiency and bias of any search method. To achieve these objectives automated methods must be developed. Because gravitational lenses are rare objects reducing false positives will be particularly important. We present a description and results of an open gravitational lens finding challenge. Participants were asked to classify 100,000 candidate objects as to whether they were gravitational lenses or not with the goal of developing better automated methods for finding lenses in large data sets. A variety of methods were used including visual inspection, arc and ring finders, support vector machines (SVM) and convolutional neural networks (CNN). We find that many of the methods will be easily fast enough to analyse the anticipated data flow. In test data, several methods are able to identify upwards of half the lenses after applying some thresholds on the lens characteristics such as lensed image brightness, size or contrast with the lens galaxy without making a single false-positive identification. This is significantly better than direct inspection by humans was able to do. (abridged)
BibTeX:
@techreport{metcalf2018strong,
author = {Metcalf, R Benton and Meneghetti, M and Avestruz, Camille and Bellagamba, Fabio and Bom, Clécio R and Bertin, Emmanuel and Cabanac, Rémi and Decencière, Etienne and Flamary, Rémi and Gavazzi, Raphael and others},
title = {The Strong Gravitational Lens Finding Challenge},
journal = {arXiv preprint arXiv:1802.03609},
year = {2018}
}

### 2016

D. Mary, R. Flamary, C. Theys, C. Aime, Mathematical Tools for Instrumentation and Signal Processing in Astronomy, 2016.
Abstract: This book is a collection of 13 articles corresponding to lectures and research works exposed at the Summer school of the CNRS titled « Bases mathématiques pour l’instrumentation et le traitement du signal en astronomie ». The school took place in Nice and Porquerolles, France, from June 1 to 5, 2015. This book contains three parts: I. Astronomy in the coming decade and beyond The three chapters of this part emphasize the strong interdisciplinary nature of Astrophysics, both at theoretical and observational levels, and the increasingly larger sizes of data sets produced by increasingly more complex instruments and infrastructures. These remarkable features call in the same time for more mathematical tools in signal processing and instrumentation, in particular in statistical modeling, large scale inference, data mining, machine learning, and for efficient processing solutions allowing their implementation. II. Mathematical concepts, methods and tools The first chapter of this part starts with an example of how pure mathematics can lead to new instrumental concepts, in this case for exoplanet detection. The four other chapters of this part provide a detailed introduction to four main topics: Orthogonal functions as a powerful tool for modeling signals and images, covering Fourier, Fourier-Legendre, Fourier-Bessel series for 1D signals and Spherical Harmonic series for 2D signals; Optimization and machine learning methods with application to inverse problems, denoising and classication, with on-line numerical experiments; Large scale statistical inference with adaptive procedures allowing to control the False Discovery Rate, like the Benjamini-Hochberg procedure, its Bayesian interpretation and some variations; Processing solutions for large data sets, covering the Hadoop framework and YARN, the main tools for the management of both the storage and computing capacities of a cluster of machines and also recent solutions like Spark. III. Application: tools in action This parts collects a number of current research works where some tools above are presented in action: optimization for deconvolution, statistical modeling, multiple testing, optical and instrumental models. The applications of this part include astronomical imaging, detection and estimation of circumgalactic structures, and detection of exoplanets.
BibTeX:
@book{mary2016mathematical,
author = {Mary, David and Flamary, Remi and Theys, Celine and Aime, Claude},
title = {Mathematical Tools for Instrumentation and Signal Processing in Astronomy},
publisher = {EDP Sciences},
year = {2016}
}
A. Rakotomamonjy, R. Flamary, N. Courty, Generalized conditional gradient: analysis of convergence and applications, 2015.
Abstract:
BibTeX:
@techreport{rakotomamonjy2015generalized,
author = {Rakotomamonjy, Alain and Flamary, Rémi and Courty, Nicolas},
title = {Generalized conditional gradient: analysis of convergence and applications},
year = {2015}
}

### 2014

R. Flamary, N. Courty, D. Tuia, A. Rakotomamonjy, Optimal transport with Laplacian regularization: Applications to domain adaptation and shape matching, NIPS Workshop on Optimal Transport and Machine Learning OTML, 2014.
Abstract: We propose a method based on optimal transport for empirical distributions with Laplacian regularization (LOT). Laplacian regularization is a graph-based regularization that can encode neighborhood similarity between samples either on the final position of the transported samples or on their displacement as in the work of Ferradans et al.. In both cases, LOT is expressed as a quadratic programming problem and can be solved with a Frank-Wolfe algorithm with optimal step size. Results on domain adaptation and a shape matching problems show the interest of using this regularization in optimal transport.
BibTeX:
@conference{flamary2014optlaplace,
author = { Flamary, R. and Courty, N.. and Tuia, D. and Rakotomamonjy, A.},
title = {Optimal transport with Laplacian regularization: Applications to domain adaptation and shape matching},
booktitle = { },
howpublished = { NIPS Workshop on Optimal Transport and Machine Learning OTML},
year = {2014}
}

### 2011

R. Flamary, Apprentissage statistique pour le signal: applications aux interfaces cerveau-machine, Laboratoire LITIS, Université de Rouen, 2011.
Abstract: Brain Computer Interfaces (BCI) require the use of statistical learning methods for signal recognition. In this thesis we propose a general approach using prior knowledge on the problem at hand through regularization. To this end, we learn jointly the classifier and the feature extraction step in a unique optimization problem. We focus on the problem of sensor selection, and propose several regularization terms adapted to the problem. Our first contribution is a filter learning method called large margin filtering. It consists in learning a filtering maximizing the margin between samples of each classe so as to adapt to the properties of the features. In addition, this approach is easy to interpret and can lead to the selection of the most relevant sensors. Numerical experiments on a real life BCI problem and a 2D image classification show the good behaviour of our method both in terms of performance and interpretability. The second contribution is a general sparse multitask learning approach. Several classifiers are learned jointly and discriminant kernels for all the tasks are automatically selected. We propose some efficient algorithms and numerical experiments have shown the interest of our approach. Finally, the third contribution is a direct application of the sparse multitask learning to a BCI event-related potential classification problem. We propose an adapted regularization term that promotes both sensor selection and similarity between the classifiers. Numerical experiments show that the calibration time of a BCI can be drastically reduced thanks to the proposed multitask approach.
BibTeX:
@phdthesis{thesis2011,
author = { Flamary, R.},
title = {Apprentissage statistique pour le signal: applications aux interfaces cerveau-machine},
school = { Laboratoire LITIS, Université de Rouen},
year = {2011}
}

### 2009

R. Flamary, B. Labbé, A. Rakotomamonjy, Large margin filtering for signal segmentation, NIPS Workshop on Temporal Segmentation NIPS Workshop in Temporal Segmentation, 2009.
Abstract:
BibTeX:
@conference{nipsworkshop2009,
author = { Flamary, R. and Labbé, B. and Rakotomamonjy, A.},
title = {Large margin filtering for signal segmentation},
booktitle = { NIPS Workshop on Temporal Segmentation},
howpublished = { NIPS Workshop in Temporal Segmentation},
year = {2009}
}
R. Flamary, A. Rakotomamonjy, G. Gasso, S. Canu, SVM Multi-Task Learning and Non convex Sparsity Measure, The Learning Workshop The Learning Workshop (Snowbird), 2009.
Abstract:
BibTeX:
@conference{snowbird09,
author = { R. Flamary and A. Rakotomamonjy and G. Gasso and  S. Canu},
title = {SVM Multi-Task Learning and Non convex Sparsity Measure},
booktitle = { The Learning Workshop},
howpublished = { The Learning Workshop (Snowbird)},
year = {2009}
}

### 2008

R. Flamary, Filtrage de surfaces obtenues à partir de structures M-Rep (M-Rep obtained surface filtering), Laboratoire CREATIS-LRMN, INSA de Lyon, 2008.
Abstract:
BibTeX:
@mastersthesis{mrep08,
author = { Flamary, R.},
title = {Filtrage de surfaces obtenues à partir de structures M-Rep (M-Rep  obtained surface filtering)},
school = { Laboratoire CREATIS-LRMN, INSA de Lyon},
year = {2008}
}